foo.py

@python_app
def square(x):
    return x**2
@python_app
def average(x):
    return sum(x)/len(x)

output_list = []
for i in range(1,5):
    output_list.append(square(i))

mean = average(output_list)
# Original <----------------------
# Edits ----------------->
@python_app
def square(x):
    return x**2

# inputs is a special kwarg that allows parsl apps to take a collection of futures
# If you pass an app a list or dict of futures, parsl doesn't inspect the data structure to see if there are futures in it.
@python_app
def average(inputs=[]):
    return sum(inputs)/len(inputs)

output_list = []
for i in range(1,5):
    output_list.append(square(i))

mean = average(inputs=output_list)